Acutaly the idea was briliant. Take the training into a non dangerous area, I'd like to see a u boat try to sail up to the Great lakes! Also a front line carrier was not talen out of service. The conversion may have cost a bit but not as much as building a new one.
Also as these ships were not armed a considerable cost saving was achieved in armaments and crew. The crew was about 250 officers and men.
The plans used for the model in FSM came from Great Lakes Research for the hull of the Seeandbee and from another museum for the actual conversion.
Dai